Publishers may request content from multiple third-party content providers as part of choosing a sponsored content item to display with the publisher content. This is often done through the use of mediation platforms that interact with the third-party content providers. The mediation platform chooses a third-party content provider and then the third party content provider network is responsible for requesting and serving the sponsored content items. Accountability for undesirable sponsored content items may be difficult when many different third-party content provider networks are serving sponsored content items.